While the U.S. may have been able to completely dominate another country in WW2, I don't see how that could happen today. Even assuming the U.S., with their military might, could take control of the Chinese government, I don't believe it would last. When the U.S. beat Japan, they were able to control the messaging and media for years, effectively training the newer generation that this was all in their best interest. With the internet and the pourus information walls, rebels could easily organize and be a never-ending challenge to any lasting dominance.